How Your Air Conditioner Works

Originally published on November 12, 2012

Understanding AC Systems: A Behind-the-Scenes Look

While most people associate air conditioning with cold, the science behind making your home cooler actually deals with the transfer of heat. When that heat is lost, or removed, the remaining cold air cools your home.  In order to understand this system better, let’s look at the major components. Your central air conditioning system has two key components: the indoor unit, and the outdoor unit. They work in tandem to keep your home comfortable year-round.

Indoor Unit

The indoor unit is typically located in a closet or basement, and is near where your furnace filter is located. The unit consists of a coil box that contains what is called an evaporator.  The evaporator allows for the refrigerant – a cooling fluid inside the coil piping sometimes known by a brand name such as Freon™ – to evaporate and absorb heat. Once the heat is absorbed from inside your home, it leaves nothing but cool air to be sent back into your home.

Just as water absorbs heat from your stove in order to boil (or evaporate) refrigerant absorbs heat from your house. This means that both water and refrigerant turn from liquid to vapor as they absorb heat.

Outdoor Unit

The outdoor unit is usually located in the rear or side of your house and it is where the heat from inside your home is dispersed. It contains the compressor, condenser coil and a fan. The heat absorbed from your home’s air is transferred to the refrigerant and then pumped to the outdoor unit. As this heat is absorbed and moved by the refrigerant to the outdoor coil, it passes through the compressor.

The compressor in your air conditioning system has the primary job of moving the refrigerant throughout the system. This is important as we can then keep reusing the refrigerant to cool our house. The refrigerant is compressed to a higher pressure, and moved through the outdoor coil known as the condenser. As the refrigerant passes through the condenser, a fan delivers ambient air across the condenser coil causing it to cool.

As the process completes, the heat from inside your house is dispersed to the air outside your house. The refrigerant is then pumped back indoors and the whole process repeats.

Did you know that making your home cooler was actually less about increasing cold air and more about removing existing heat?

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34 thoughts on “How Your Air Conditioner Works

  1. This article provides a concise yet comprehensive explanation of how air conditioners function, detailing the intricate processes that keep our environments cool and comfortable. It effectively breaks down complex concepts into easily understandable steps, making it accessible to readers of all levels of expertise.

  2. I am immensely grateful for stumbling upon the Air Conditioner Works article. It provided invaluable insights and tips that helped me troubleshoot issues with my AC unit, saving me both time and money on unnecessary repairs. Thank you for sharing such informative content that empowers homeowners like me to maintain and optimize our cooling systems efficiently!

  3. I love how this article breaks down complex concepts into easily digestible information. Learning about the condenser coil and how it releases heat outside was eye-opening. Do you have any advice on landscaping around the outdoor unit to ensure proper airflow and efficiency?

  4. How much temperature drop does a well running air conditioner give? When the temp outside is 82 F and the duct reads 70 F and air filter is clean, does it mean that the AC unit needs recharging or is a 12 degrees drop acceptable for a house AC?

  5. I noticed the same problem with my brand new unit and had to argue with my installation company about fixing it because I’m female. I know the basics: when you set the heating for 70 for example it should kick on a few degrees below 70 and should heat to a few of degrees above 70 before shutting off. You DO NOT want your unit starting and stopping all the time it’ll wear it down and will not accomplish much.
    It’s a programming thing. Call your installation company and ask them to please come out and program it correctly.

  6. I have an air cooling system in my house but lately, I have noticed that it is not working properly. And when I talked to the providers, they said it would be fixed automatically.

    I am asking you for help now, is there any permanent solution? Thank you in advance.

  7. I have moved into a senior apartment, the AC runs all day long without cutting off until late in the evening . When I ask about it they said it would do that because it is so hot outside. Was just wondering, am I old and stupid? Because at my old apartment it didn’t do that. Thank you for your help.
    Mrs. Brewster

  8. I have a brand new heat pump. Yes the filters are aways clean. I set it at 79 in the summer it comes on every 20 minutes or less and might run 5 minutes if I’m lucky.
    So when it comes on I run in there and turn it to 77 so it will run for 15 minutes and it won’t come back on for two hours or more. Yes my house is well insulated. It seems it’s cheaper for it to come on and run for 15 minutes than coming on every 15 minutes. Should I move my thermostat?
    It cost money for it to start up every 15 minutes. It does the same thing in the winter…every 10 or 15 minutes and runs for 6 or 7 minutes. Help is appreciated.
    It is under warranty and they have checked it out from top to bottom and can’t find anything wrong.

    • There is no problem with your system. New thermostats are different in how they run. Old school mercury was 2° below set point to 2° above. New digital stats work differently. They are set with a algorithm that monitors 10 events. So every time ur ac/heat comes on it monitors and drops the oldest. This allows it to run ur hvac at peak efficiency. U May walk by tstat and it’s set for 73° yet system is running. This is normal.

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